Re: [PATCH v5 3/3] arm64,ppc64le/kdump: pass dm-crypt keys to kdump kernel

Rob Herring
2026-03-30T11:44:29Z

On Wed, Feb 25, 2026 at 12:04 AM Coiby Xu <coxu@redhat.com> wrote:
>
> CONFIG_CRASH_DM_CRYPT has been introduced to support LUKS-encrypted
> device dump target by addressing two challenges [1],
> - Kdump kernel may not be able to decrypt the LUKS partition. For some
> machines, a system administrator may not have a chance to enter the
> password to decrypt the device in kdump initramfs after the 1st kernel
> crashes
>
> - LUKS2 by default use the memory-hard Argon2 key derivation function
> which is quite memory-consuming compared to the limited memory reserved
> for kdump.
>
> To also enable this feature for ARM64 and PowerPC, the missing piece is
> to let the kdump kernel know where to find the dm-crypt keys which are
> randomly stored in memory reserved for kdump. Introduce a new device
> tree property dmcryptkeys [2] as similar to elfcorehdr to pass the
> memory address of the stored info of dm-crypt keys to the kdump kernel.
> Since this property is only needed by the kdump kernel, it won't be
> exposed to user space.
>
> [1] https://lore.kernel.org/all/20250502011246.99238-1-coxu@redhat.com/
> [2] https://github.com/devicetree-org/dt-schema/pull/181
>
> Cc: Arnaud Lefebvre <arnaud.lefebvre@clever-cloud.com>
> Cc: Baoquan he <bhe@redhat.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: Kairui Song <ryncsn@gmail.com>
> Cc: Pingfan Liu <kernelfans@gmail.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Krzysztof Kozlowski <krzk@kernel.org>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Thomas Staudt <tstaudt@de.ibm.com>
> Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
> Signed-off-by: Coiby Xu <coxu@redhat.com>
> ---
> arch/arm64/kernel/machine_kexec_file.c | 4 ++++
> arch/powerpc/kexec/elf_64.c | 4 ++++
> drivers/of/fdt.c | 21 +++++++++++++++++++++
> drivers/of/kexec.c | 19 +++++++++++++++++++
> 4 files changed, 48 insertions(+)

Acked-by: Rob Herring (Arm) <robh@kernel.org>